1. Dynamical Mass Ratios of the Youngest Low-Mass Stars
Gregory Mace
Mentor: Lisa Prato
Northern Arizona University
Physics and Astronomy

2. This Project Goal: To measure mass ratios of very young binary stars.
Why: To calibrate
the parameters used
in models of young
star formation.
How: High resolution IR
spectroscopy of young
spectroscopic binaries.

3. All are pre-main sequence single-lined spectroscopic binaries.
Target Objects
RX J
P= days e= SpT= K7-M0
NTTS
P= days e= SpT= K2
NTTS
P=16.93 days e= SpT=M3
All are pre-main sequence single-lined spectroscopic binaries.

4. Introduction

5. Introduction Why infrared? Flux Ratio Closer to Unity
Reference: Web

6. Observations
Data from the instrument CSHELL on the 3-meter NASA IRTF Telescope.
NASA IRTF
CSHELL

7. Observations
Data from the instrument NIRSPEC on the Keck II Telescope.
Keck
NIRSPEC

8. Spectral Changes
NTTS
CSHELL
NIRSPEC

9. Spectral Changes
RX J
NIRSPEC

10. Parameter Determination
Two-Dimensional Cross Correlation
(Dashed line)
(Solid line)
Spectrum Compared to Templates

11. Mass Ratio Determination
RX J
Mass ratio:
q = - slope
Center of Mass Velocity:
 = (y-intercept)/(1+q)
O. C. Wilson (1941)

12. Mass ratio and center of mass velocity to be determined.
Results
RX J
q= 0.93 ± = ± 1.69 km/s
periastron  0.12 AU
apastron  2.56 AU
NTTS
Mass ratio and center of mass velocity to be determined.
NTTS

13. Results

14. Future Research RX J0529.3+1210 Future work: Observe RX J0529.3+1210
Complete mass ratios for NTTS stars

15. Conclusions The mass ratio of RX J0529.3+1210 is near unity.
RX J is the most eccentric pre-main-sequence spectroscopic binary know.
RX J has 24m excess which my be evidence of a circumbinary debris disk.
Planet formation in RX J is unlikely.
Comparison of templates supports likelihood of lower mass ratios for NTTS stars.